She did it much like a t-shirt quilt, using a lightweight fusible interfacing.
I quilted it with Popcorn, Lite Chambray Permacore thread and Hobbs 80/20 batting.
This Christmas one is the only one that gave me a bit of trouble, as the brim was quite worn out and not totally attached.
We fused his name on the top border, too.
All in all, I LOVE how it turned out and what a great idea for doing something for those onsies they have outgrown. It's an heirloom for sure!